Chapter Two. Communication and the Use of Language

A domain model can be the core of a common language for a software project. The model is a set of concepts built up in the heads of people on the project, with terms and relationships that reflect domain insight. These terms and interrelationships provide the semantics of a language that is tailored to the domain while being precise enough for technical development. This is a crucial cord that weaves the model into development activity and binds it with the code.

This model-based communication is not limited to diagrams in Unified Modeling Language (UML). To make most effective use of a model, it needs to pervade every medium of communication. It increases the utility of written text documents, as well as the informal diagrams and casual conversation reemphasized in Agile processes. It improves communication through the code itself and through the tests for that code.